Question

1.         Calculate the angular momentum of the Sun and compare it to the sum angular momentum of the planets (of their orbits only).

Answer 1

Rotational Angular momentum of a sphere of mass M and radius R is given by:

for Sun, T = period of rotation = 24.6 days = 24.6 x 24 x 3600 seconds

R = 695500000 meters and M = 1.989 x 10³⁰ kg

this gives, L_sun = 1.137 x 10⁴² kgm²/s

Orbital angular momentum of the planets is:

where R is the distance from the planet to Sun and T is the period of one complete revolution.

For Mars, M = 3.3 x 10²³ kg, R = 58 x 10⁹ m and T = 87.97 days

=> L_mercury = 9.177 x 10 kgm²/s

Repeat for other planets.